Time measurements with digital logic require clocks running at ultra-high frequencies in order to precisely measure the time of events having very short time periods, e.g., 100 picoseconds. Clocks running at ultra-high frequencies, e.g., 1-10 GHz, driving logic capable of running at about 1 GHz, would require a great deal of power to run the clock and logic circuits, and, in addition, the clock and digital logic circuits operating at these clock speeds would generate a great deal of circuit noise.